The present invention relates to a data storage tape cartridge. More particularly, it relates to a hybrid belt-driven tape cartridge with optimized performance characteristics.
Data storage tape cartridges have been used for decades in the computer, audio and video fields. While other forms of media storage are also available, the data storage tape cartridge continues to be an extremely popular form of recording large volumes of information for subsequent retrieval and use.
A variety of different data storage tape cartridge designs are currently available. In general terms, a data storage tape cartridge consists of an outer shell or housing maintaining at least one tape reel hub and a length of magnetic storage tape. The storage tape is wrapped about the hub and is driven through a defined tape path by a driving system. The housing typically includes an opening (or window) of some type for allowing access to the storage tape by a read/write head upon insertion of the cartridge into a tape drive. This interaction between storage tape and head may take place within the housing (e.g., a mid-tape load design), or the storage tape may be directed away from the housing to an adjacent area within the tape drive at which the head is located (for example, with a helical drive design or a leader block design). When the tape cartridge/drive system is designed to direct the storage tape away from the housing, the data storage tape cartridge typically includes a single tape reel. Conversely, where the tape cartridge/drive system is configured to provide head/storage tape interaction within or very near the housing, a two- or dual-tape reel assembly configuration is utilized.
Dual reel-type tape cartridges are further categorized according to the system used to drive the storage tape. More particularly, dual reel tape cartridges are either belt-driven or spool- (or hub-) driven. Both designs present certain advantages as outlined below.
The belt-driven tape cartridge has been known for many years and is described, for example, in U.S. Pat. No. 3,692,255 (von Behren), incorporated herein by reference. As illustrated in FIG. 1, a typical, prior art belt-driven tape cartridge 10 includes a housing 11 that contains a length of the storage tape 12 that is wound about a pair of tape reel hubs 12 (thereby defining xe2x80x9ctape packsxe2x80x9d). The housing 11 also encloses a pair of corner rollers 13 and a drive roller 14. An elastic drive belt 15 is stretched around the rollers 13 and 14 and the tape packs on the hubs 12. The drive roller 14 is accessible by a drive puck (or capstan) 16 of a tape drive through an opening 17 formed at the front of the housing 11.
Similarly, a window 18 is formed to allow a read/write head 19 to engage the storage tape 12. Movement of the drive roller 14 by the capstan 16 causes the drive belt 15 to move, and frictional engagement between the drive belt 15 and the storage tape 12 then causes the storage tape 14 to move. In addition to moving the storage tape 12, the drive belt 15 provides proper tension in the storage tape 12, especially at the read/write head 19. The storage tape 12 can be moved and read in either direction, (i.e., either hub can serve as the supply hub and either as the take-up hub).
The belt-driven tape cartridge is highly viable and relatively inexpensive, but may present certain tape drive registration issues, as well as power and speed losses during use due to the rubber-coated capstan 16. In addition, as is evidenced by FIG. 1, the drive roller 14 and hubs 12 are typically symmetrically arranged so as to optimize the cartridge layout. However, because the capstan 16 must pass through an opening 17 in the housing 11 to engage the drive roller 14, the head access window 18 must be offset from the drive roller 14. As a result, the hubs 12 are asymmetrically arranged relative to the head access window 18. This design constraint may adversely affect cartridge performance, as the head/storage tape interface cannot desirably occur at the bi-sector of the hubs. Further, location of the drive roller 14 relative to the head access window 18 dictates that guide pins or rollers are the only tools available to effectuate tape guidance across the head access window 18. It would be virtually impossible to incorporate an elongated tape guide that would otherwise provide beneficial xe2x80x9cflyingxe2x80x9d guidance. Finally, industry-accepted form factors associated with currently available belt-driven tape cartridges prevents implementation of other components that might alleviate one or more of these potential concerns.
The spool-driven tape cartridge overcomes several of the concerns associated with the belt-driven design by forming the tape cartridge drive system to directly engage and drive (or rotate) the tape reels hubs. An example of a spool-driven tape cartridge is provided in U.S. Pat. No. 6,069,777 (Vanderheyden et al.), the teachings of which are incorporated here by reference. In general terms, the housing associated with the spool-driven tape cartridge forms two openings that are axially aligned with the tape reel hubs. The tape drive, in turn, includes two motorized, splined drive chucks that are directed into axial engagement with the respective tape reel hubs, via the openings, for subsequent controlled rotation thereof. In this regard, the tape reel hubs and splined drive chucks include corresponding toothed portions to facilitate driving engagement therebetweeen. Because the tape reel hubs are directly driven, the spool-driven tape cartridge eliminates the need for a drive belt, thereby obviating the power and speed losses otherwise experienced with belt-driven tape cartridges. However, because the drive belt is no longer included, a complex and expensive tension servo system must be incorporated into the tape drive to ensure proper tape tension at the read/write head. This requirement, in combination with the two motorized drive chucks, renders the spool-driven tape cartridge drive system relatively expensive, especially as compared to a belt-driven system. Further, similar to the belt-driven tape cartridge, industry-accepted form factor size associated with spool-driven tape cartridges limits the ability to implement additional features that might otherwise improve performance. For example, with available spool-driven tape cartridges, the tape reel hubs are asymmetrically arranged relative to the head access window, possibly affecting tape tension.
Data storage tape cartridges are important tools used to maintain vast amounts of information. With respect to dual reel cartridges, belt-driven and spool-driven designs offer certain advantages as well as potential disadvantages. Presently, no efforts have been made to derive a tape cartridge incorporating these features, due in large part to industry acceptance of current designs and the high costs of effectuating such a design. Therefore, a need exists for a hybrid tape cartridge and related tape drive that combines the features of the belt-driven and spool-driven cartridges on a low cost basis.
One aspect of the present invention relates to a data storage tape cartridge including a housing, first and second tape hubs, a storage tape, a drive roller, first and second corner rollers, and a drive belt. The housing defines a head access window. The first and second tape hubs are rotatably mounted within the housing. The storage tape is wound about the first and second hubs to form first and second tape packs thereabout. The drive roller and the first and second corner rollers are rotatably mounted within the housing. The drive belt is stretched about the drive roller, the first and second tape packs, and the first and second corner rollers. Finally, the first and second hubs are symmetrically arranged relative to the head access window. This symmetrical arrangement optimizes cartridge performance during use. In one preferred embodiment, the housing forms an opening along a major surface for allowing axial access to the drive roller by a splined drive chuck of a tape drive. With this one preferred embodiment, and unlike prior art belt-driven tape cartridges, a capstan does not engage the drive roller, but instead the drive roller is engaged by a motorized splined drive chuck. Alternatively, the hubs can be axially engaged and rotated by two motorized drive chucks. In yet another preferred embodiment, the housing is sized such that the first and second corner rollers are configured to each include a magnetic hysteresis-type brake.
Another aspect of the present invention relates to a data storage tape cartridge including a housing, first and second tape hubs, a storage tape, a drive roller, first and second corner rollers, and a drive belt. The housing defines a head access window. The first and second tape hubs are rotatably mounted within the housing. The storage tape is wound about the first and second tape hubs to form first and second tape packs thereabout. The drive roller and the first and second corner rollers are rotatably mounted within the housing. The drive belt is stretched about the drive rollers, the first and second tape packs, and the first and second corner rollers. Finally, the drive roller is aligned with the head access window. With this configuration, upon engagement of the tape cartridge with a tape drive that includes a head, interaction between the head and the storage tape at the head access window impedes radial access to the drive roller. As such, at least one of the drive roller, first tape hub or second tape hub must be axially accessed and driven by a motorized splined drive chuck. In one preferred embodiment, the tape cartridge further includes a base plate having first and second reference portions such that the tape cartridge provides three datum locations for registration by a registration device.
Yet another aspect of the present invention relates to a combination data storage tape cartridge and a tape drive. The data storage tape cartridge includes a housing, first and second tape hubs, a storage tape, a drive roller, first and second corner rollers, and a drive belt. The housing defines a head access window. The first and second tape hubs are rotatably mounted within the housing. The storage tape is wound about the first and second hubs to form first and second tape packs thereabout. The drive roller and the first and second corner rollers are rotatably mounted within the housing. The drive belt is stretched about the drive roller, the first and second tape packs, and the first and second corner rollers. The tape drive includes a motorized drive chuck for engaging and rotating one of the drive rollers, the first tape hub and the second tape hub. Further, the tape drive does not include a capstan for otherwise driving the drive roller. Unlike prior art belt-driven tape cartridge drive systems, the combination tape cartridge and tape drive of the present invention combines belt-driven and spool-driven design features, resulting in an inexpensive, highly efficient system.
Yet another aspect of the present invention relates to a tape drive for driving a data storage tape cartridge that includes a drive belt stretched about a drive roller and two tape packs. The tape drive comprises a rotatably driven, splined drive chuck configured to axially engage and rotatably drive the drive roller. In one preferred embodiment, the tape drive further includes a read/write head for transferring information to and from storage tape maintained by the tape cartridge. In this regard, the drive chuck is aligned with the read/write head.
Yet another aspect of the present invention relates to a data storage tape cartridge, first and second tape hubs, an elongated tape guide, a storage tape, a drive roller, first and second corner rollers, and a drive belt. The housing defines a head access window. The first and second tape hubs are rotatably mounted within the housing. The storage tape is wound about the first and second hubs to for first and second tape packs thereabout. The elongated tape guide is positioned adjacent the head access window and has a length greater than a length of the head access window. The elongated tape guide guides the storage tape across the head access window. The drive roller and the first and second corner rollers are rotatably mounted within the housing. The drive belt is stretched about the drive roller, the first and second tape packs, and the first and second corner rollers. In one preferred embodiment, the elongated tape guide is located between the head access window and the drive roller and provides for flying guidance of the storage tape at elevated tape speeds.